Drive for electric generators



A. 1 ARMENTROUT 2,349,334 DRIVE v FOR ELECTRIC GENERATORS May 23, 1944.

Filed Sept. 23, 1942 3 Sheets-Sheet 2 May 23, 1944. A L ARMENTRQUT2,349,334

DRIVE FOR ELc'rnrc GENERATons Filed sept. 2s. 1942 s sheets-sheet s`Patented May 23, 1944 UNITED STATES 'PATENT OFFICE 2,349,334 nmvE FoaELECTRIC GENERATORS Y Arthur r.. Am'emmut, Lung Beach, Calif.

Application September 23, 1942, Serial No. 459,414

` (ci. 29o- 4) 14 Claims.

This invention has to do with a drive for electric generators andrelates more particularly to a generator drive for aircraft. A generalobject of the present invention is to provide a simple, practical anddependable drive suitable 'for the generation of alternating currentfrom the engine or engines of an aircraft.

It is common practice in aircraft and particularly military aircraft toemploy direct current electrical systems and to generate the electricityby means of generators driven -directly from the engine or engines ofthe aircraft. ASuch 'systems involve heavy conductors and have certaincharacteristics that are not altogether desirable in aircraft.

It is desirable in aircraft, and particularly in military aircraft, ifalternating current is employed, to have such current at a predeterminedcycle. Heretofore this has presented 'certain practical dlmculties sincethe engines of the aircraft depended upon for power are not operated atconstant speeds but in practice may vary widely in their speeds ofoperation and they usually vary in speed between one engine and another.With the usual drive connections between such engines and alternatingcurrent generators the alternating current would vary widely as tocycle.

It is an object of this invention to provide an effective practicalalternating lcurrent system for aircraft employing the engine or enginesof the aircraft as the prime mover or source of power to generateelectrical energy at a remote point or points. By the invention thedrive of the generator or generators is through fluid making it possibleto locate the generators most advantageously either from'the standpointof weight distribution or proximity to the electrical units to bedriven, or both.

Another object of this invention is to provide a drive from a variablespeed engine such as is employed to propel an aircraft to a generatorwhereby the generator is operated to develop alternating current at alpredetermined cycle regardless of the 'speed at which the engine isoperated.

It is another object of this invention to provide two or more drives.ofthe character described which normally operate independently of eachother but which are interconnected to supplement each other in case ofemergency.

It is another object of the present invention to provide interconnectedelectrical generating units of the character described which have safetyelements incorporated in them which minimize the danger of breakdown dueto damage or injury to the various elements of the units.

Another object of the invention is to provide a drive of the characterdescribed in which there is a final delicate throttle control for theprime movers operating to supplement the general control system so thatthe speed regulation is precise. A

A further object of the invention is to provide a final throttle controlthat involves an alternating current circuit energized by the generatorbeing driven.

I'he various objects and features of the invention will be best and morefully understood from the following detailed description of typicalmanners of carrying out the invention, throughout which description Imake reference to the accompanying drawings, in which:

Fig. 1 is a schematic or diagrammatic yView illustrating a typicalembodiment of the inveninvention. Fig. 6 is a view showing another formof Apressure generator that can be used in carrying out my invention.

'I'he present invention is primarily concerned with the provision of apractical means of generating alternating current of a predeterminedcycle from a variable speed prime mover. The invention is particularlyimportant as applied to aircraft since in such craft the practicalavailable source or sources of power are the enginel or engines of thecraft which operate at widely different speeds under differentconditions, Whereas an alternating current electrical system isdesirable in such craft but must, in practice, be of constant cycle.

'Ihe present invention in its simpler form provides a drive between aprime mover such as an aircraft engine and an electrical generator suchas an alternating current generator which drive is through fluid underpressure enabling the generator to be located wherever desired withrelation to the engine or the craft. and also automatically operates tocompensate for variations in engine speed so that the generator isalways operated at a uniform speed.

The invention further contemplates the employment of two or more suchgenerating units interconnected so that they supplement one another in amanner to prevent failure of the source of electrical energy in theevent that one engine should become disabled, and also to proteotagainst unexpected breakdown in the units such as might cause onedamaged unit to render the connected unit which is undamaged inoperative. The invention further provides a throttle control that effects afinal synchronizing regula tion of the engines so that the generatorsall operate at exactly the same speed. This control is throughalternating current generated by the system. i

In the drawings Fig. 1 illustrates two generating units interconnectedin accordance with the present invention. It is to be understood ofcourse that these two units' may be located close together or may beremote from one another. Because of the manner in which the two unitsare illustrated I will refer to them as the upper and lower units, theupper unit being the one shown uppermost in Fig. 1 and the lower unitbeing the one shown at the bottom of Fig. 1.

A unit embodying the invention includes, generally, a pressure generatoror fluid pressure pump A operated by an engine or other suitable primemover B, a motor C driven by pressure from the pressure generator A andhaving driving connection with an electrical power generator D, andmeans E for regulating the fluid supplied to the motor C so a constantpressure is kept on the motor C whereby it is operated at a constantspeed. -The invention further provides a iluid supply means F whichserves to keep the unit supplied with huid. at a substantially constanttemperature so that there 'is no variation in performance due to achange in viscosity o! the fluid used in the system. Fur ther the unitincludes an overrunning clutch J in the connection between the motor Cand generator D, a manually controlled lay-pass means H which cuts outthe automatic controls to facili-- tate starting.

In Fig. 1 of the drawings `III have illustrated the unit provided by theinvention as involving a pressuregenerator A directly coupled to ordriven by the engine B of an aircraft. I have shown but a fragment ofthe aircraft engine IB and I have shown the generator A operated by ashaft IIJ from the engine. In the particular form of the invention underconsideration the pressure generator A is of a type in which the outputmay be effectively regulated by controlling the supply of fluid to thegenerator. I have illustrated diagrammatically a multiple stagecentrifugal pump as the pressure generator. The pump A receives the duidfrom a supply line II and delivers it to a pressure line I2.

'I'he supply line II connects the intake ol' the pump A with the fluidsupply means F. The fluid supply means may, in accordance 'with theprinciples of the invention, be of any desired form or type and may be,located wherever de sired in the craft. In the diagram I have shown thesupply means as including a container I3 for carrying a body or supplyof fluid for the unit. In practice `the fluid employed will ordinarilybe oil and, therefore, for sake of reference I will refer to the duid asbeing oil. 'It bew ing understood of course that any suitable fluid maybe employed without departing from the spirit of the invention.

The supply pipe II is related to the container' I3 so that fluid fromthe container .will be fed to the supply pipe regardless of the positionin which the container may ce located. Aircraft are commonly maneuvercdthrough various positions requiring that the operating units containedtherein must operate at various angles or even in completely reversedpositions. It is contemplated that the container I3 will at all times hemore than half filled with fluid and the supply pipe II is provided withan extension II*l within the container extending to the center thereofso that regardless of the position of the container oil will always feedinto the supply pipe.

The fluid supply means F includes a means for conditioning the oil sothat .it is always at a constant temperature. In practice the meansprovided for regulating the temperature of the oil may be incorporatedin various parts of the unit. However, for most practical purposes itmay be incorporated in or at the container I3 as indicated in thediagram in Fig. 1. In this case a coil I4 is provided in the containerI3 designed to carry a medium for heating or cooling the oil in thecontainer I3, as circumstances recuire. The coil I4 is supplied with thethermal medium through a supply pipe I5 and a suitable discharge I8 isprovided to conduct the medium away from the coil. A regulating valve I1is provided in the supply pipe I5 under control of a thermostat I8 sothat the rate of ilow of the thermal medium through the coil I4 isgoverned by the temperature of the oil in the container I 3. It will beunderstood, of course, that the thermal medium circulated through thecoil may be either such as to heat the oil or cool the oil ascircumstances require, and such medium may be generated in any desiredmanner or may be taken from other units of the craft.

The delivery or pressure line I2 extends from the outlet or delivery ofthe pump A to the mo- 'tor C. However, in accordance with the inven tionvarious elements or units or equipment are connected in the pressureline as will be hereinafter described. These elements may be referred togenerally' as a cut-oil means 20, a check valve 2l, a control valve 52,an accumulator 22, a safety valve 23, and a throttle valve 35.

The cut-off means 20 and control valve 52 are employed when severalunits are interconnected. There is a cut-oif means 2l) for each unitwhich acts as I will hereinafter describe t0 cut ofi the fluidconnections at the pressure generator in the event that the pressuregenerator or the motor should he disabled or cease operation. The checkvalve 2l is located between the pressure generator A and the accumulator22 and acts to allow flow of oil 4through the pressure line I2 only awayfrom the generator A.

The accumulator 22 which may be located at Aany convenient point in thecraft is in Ithe nature of a container 2l designed vto carry a suitablebody oi oil and a suitable quantity of en* trapped eras or air. In thearrangement illustrated the container 2t of the accumulator is connectedin the pressure line I2 so that the line enters at `the bottom of thecontainer and passes out through the top of the container. .An extension.25 of the outgoing portion of the pressure line projects into thecontainer 24 to approximately the center thereof so that the outgoingpressure line is supplied with oil regardless of the positioning of thecontainer 24.

The pressure line I 2 extending from the accumulator 22 is connected tothe motor C so that the uid under pressure in the accumulator passesdirectly from the accumulator to the motor through controls 45 and 85.In accordanceI with the invention it is of prime importance to have aconstant pressure on the oil in the pressure line from the accumulatorto the motor C. Various means may be employed to accomplish this. In thecase illustrated it is contemplated that the unit be adjusted or set tooperate so that pressure is supplied by the pump A to always be slightlyabove the pressure desired at the motor C. The accumulator 24 absorbsany surge or fluctuation in pressure incidental to the regulation of thegenerator pressure accomplished through the means E. Stabilized pressuresupplied to the motor C assures constant operation of the motor. Thepressure in the accumulator 22 being slightly above that desired at themotor C a safety or pressure relief valve 23 is provided in the pressureline from the accumulator to the motor to let off excess pressurereturning the oil thus blcd from the pressure line through a suitableconnection .30 to the container I3 of the means F. The valve 23 not onlyacts as a safety device to prevent excess pressure from developing inthe system but also acts as a means for stabilizing` the pressuresupplied for the motor C.

The motor C is a fluid motor of a positive type -designed to be operatedby a fluid such as oil.

The means E thus far described will supply a predetermined quantity ofoil to thesupply line I2. To stabilize the speed of operation of themotor C I provide lmeans for regulating the quantity and pressure of theoil delivered to the motor. This means includes a volume control inconnection with the pressure control and a throttling system hereinafterdescribed. The volume control may comprise an orifice fitting 45 locatedimmediately ahead of the throttle valve 85, the fitting being providedwith an orifice plate 46 having an aperture to pass the desired amountof fluid at the pressure established as hereinabove Y described.

In practice any one of several well known forms or styles of fluid motormay be employed as the motor C. It may be a vane type motor, a gear typeor a cylinder and piston type. It is preferred that the motor C drivethe generator D through an overrunning clutch J so that the generatormay run ahead of the motor. The assembly formed by the motor C andgenerator D and clutch J may be located at any desired point in theaircraft. For instance, this assembly may be located in a manner toplace the weight thereof in the mostv advantageous manner, or it may belocated to minimize electrical wiring that may be hazardous or it may belo- I cated so that the electricity is generated in close proximity tothe points at which it is used. l

The oil after having passed through the motor C is discharged therefromthrough a-return line II'a which conducts it to the container I3 of themeans F. It is preferred to include the check valve 3l in the line IIbwhich operates to allow the oil to pass freely from the motor C into thecontainer I3 but prevents reverse flow.

The means E for regulating the fluid functions so that iiuid at apredetermined pressure and in a predetermined volume reaches the motorto operate it at a certain speed. When a multiple stage centrifugal pumpis used as the pressure generator A the control means E includesaircontrol valve 4I) in the supply line II adjacerit the intake of thepump A and suitable means for regulating the valve 40. In the caseillustrated the valve 40 is under control of a diaphragm mechanism 4Iactuated by pressure from the pressure line I2 leading from the`accumulator 22 to the throttle valve B5. A suitable pressure connection42 extends from the said pressure line I2 to the diaphragm 4I so thatthe position of the valve 40 is varied with the pressure at the outletfrom the accumulator.

In practice it may be desired to control the temperature of the oil inthe accumulator 22 in addition to or in place of controlling it in thereservoir I3. In the drawings I have indicated a thermal coil I4 in theaccumulator connected with conduits I5a and I6al for handling the ther'`mal medium, either a heating or cooling medium,

maintain a uniform back pressure in the motor.h

With this arrangement, that is, by providing an orifice fitting 41, thereservoir or supply means may be open to atmospheric pressure or may beclosed and subject to some pressure, as circumstances require.

Tlie operation of the unit thus far described will be apparent from thedrawings. The aircraft engine B drives the pressure generator A which issupplied with oil under control of the regulating valve 40. The oilunder pressure delivered by the generator A passes the check valve 2l,enters the accumulator 22 and is delivered from the accumulator to thelpressure line I2 extending from the accumulator to the motor C. Thesafety valve 23 relieves any excesspressure, by passing any excess oilthrough connection 30 to the supply means F. The orifice fitting 45controls the volume of oil passed to the motor and the throttle valve85, the operation of which is described later,

is provided for final regulation. The oil delivered under pressure tothe motor C drives the motor which in turn drives the generator Dthrough the overrunning clutch J. The motor generator set C D operatesat a constant speed so that the generator D which Ais an alternatingcurrent generator delivers alternating current at a constantpredetermined cycle. The oil discharged after passing throughthe motor Cpasses the check valve 3l and the orifice fitting 41 and enters. themeans F where it is established at a proper temperature and returned tothe pressure generator A through the supply line II.

The present invention contemplates the interconnection of two or moreunits such as I have just described so that the units supplement eachother and so that the genera-tors of several connected units operate atexactly the same speed. In Fig. l of the drawings I have illustrated asim ple fluid pressure interconnection of two units which under normalcircumstances operate as individual units. This interconnection servesto connect the units so that one may assist the other.

may be supported in any suitable manner to be freely rotatableconcentric with the pinions. It is common to make the ring in the formof a case that houses the mechanism. The worm wheel 89 of thedifferential mechanism meshes with a worm gear or segment 9,2 having apivotal axis 83. The segment 92 is rotated on its axis whenevcer thefloating element 88 of the differential rotates. The direction in whichthe segment 92 is swung depends upon the direction of rotation of theelement 89. Any suitable mechanical connection may be provided betweenthe segment 92 and the throttle 'valve 85. `A simple link connection 94s shown connecting an ex tension of the segment 82 with the stem of thevalve 85.

The electrical connection provided by my invention contemplatesutilization of the alternating current generated by the generators G' sothat any variation in speed of operation of the generators isimmediately reflected in the operation of the synchronous motors causingoperation of one of the throttle valves to correct the lack ofsynchronization.

In the form of the invention illustrated the generators G `operate togenerate a three phase alternating current and the two synchronousmotors 86 and 81 of each unit controlling a throttle valve are designedto be operated by the current from the generators so that the speed ofany particular synchronous motor will correspond exactly with that ofthe generator with which it is connected.

The system of the present invention provides, generally, for anelectrical system connecting the generators G' of the units and thesynchroe, nous motors connected with the throttles so that the twomotors of one unit are energized from one generator G while thatgenerator energizes only one of the motors of the other unit, the secondmotor of said other unit being energized from the other generator G. Itwill thus be apparent that if the two generators G' are not insynchronism the synchronous motors of the throttle valve for said otherunit will not be in synchronism and as a result that throttle valve willbe operated until the lack of synchronism is corrected. The system alsoprovides suitable switches and a selecting means whereby the operatormay elect to make either one of the generators G' the master to whichthe other is adjusted, and the operator may, at will, speed up or slowdown the master generator to gain the desired electrical output from thesystem.l

In Fig. 5 of the drawings I have illustrated a simplified diagram inwhich each single line represents the several conductors necessary forthe three phase circuit. In the diagram, Fig. 5, the synchronous motordiierential throttle control of the lupper;` unit is illustrated at Xand the synchronous motor differential throttle'control of the lowerunit is illustrated at Y. The

master selector is illustrated at Zand the con-l trol switching meansfor varying the speed of the master generator is illustrated at S.

Current from the generator G' of the upper unit is carried by connectionto terminal |0 of the master selector Z. Current from generator G' oi'the lower unit is carried by connection |02 to the terminal |03 of themaster selector. 'The control arm |04 of the master selector can bethrown into contact with either of the contacts |0| and |03. The controlarm |08 connects with a connector |05 extending from the masten selectorto the synchronous motor 80 of the upper unit S and with connector |08conchronousr motors of necting with the synchronous motor 86 of the unitY. A connection H0 connects the generator G' of unit X with synchronousmotor 81 of that unit while a connection connects the generator G ofunit Y with the synchronous motor 81 of unit Y.

When the control member |04 of the master selector Z is positioned toengage contact |0| as shown in the diagram, generator G of unit X feedsthe connections |05 and |06 so that the synchronous motors 86 of the twounits are driven by and operate in synchronism with he generator Gf ofunit X. Synchronous motor 81 of unit X being connected with thegenerator G' of that unit by connection ||0 operates at the same speedas motor 86 and therefore the unit X becomes a master or iixed unit.

It will be apparent that as the motors 86 and 81 at unit X operate atexactly the same speed because they are both energized from the commongenerator G' the diierential mechanism of that unit will not operate tovary the throttle valve thereof. However, with the setting justdescribed the synchronous motor 86 of unit Y is energized from generatorG' of unit X while the synchronous motor 81 of unit Y is energized fromtheA generator G' of unit`Y through connection The throttle mechanism ofunit X is not varied while the generator of unit X is connected throughthe master selector Z because both synthat unit are necessarilyoperating at the same speed. However, the synchronous motors of the unitY being operated one from the generator of the unit X and the other fromthe generator of unit Y the diierential of unit Y is subject tooperation to regulate the throttle valve 85 of unit Y. If for any reasonthe generator G' of unitYvaries in speed from that of unit G there willbe a difference in speed of operation between the synchronous motors 86and 81 of unit Y. This variation in speed or lack of 'synchronism wlilbe reflected through the differential mechanism 88 of unit Y to operatethe throttle valve 85 in the appropriate direction to either speed up orslow down the motor driving generator G' of unit Y, as the case may be,

` until such time as synchronization is re-established.

It will be apparent selector Z either unit master unit so that relativethereto.

The control switching means S is provided primarily to provide a meanswhereby the speed of the control or master unit, as selected through themaster selector Z, may be varied as desired. In practice one of theunits having been selected as the master unit to which the other unit ismade to synchronize, it may be desired to speed up or slow down themaster unit in order to gain the desired electrical output.

The contol switching means includes a series of reversing. switchespreferably under a single manual control. In the diagram I haveindicated a series of' reversing switches on a single operating rod |20under control of an operating lever |2I. The several switches involvedin the means S are reversing switches there being a reversing switch |22in connection |05, a reversing switch |23 in connection ||0, a reversingswitch |24 in connection |08 and a reversing switch |25 in connectionill. It will be noted that switches |22 and |23 connect with unit XWhereas switches |24 and |25 connect with unit Y.

that through the master may be established as the the other unit isadjusted lli/.ith the master selector Z set as shown in the diagram.' sothat unit X is the master or control unit, the speed of operation of thegenerator G ci unit X can be varied only by obtaining a differential inthe operation oi the two synchronous' motors driven by the generator G'of that unit. To accomplish this the reversing switches |22 and |23 Jareconnected with the rod I20 so that when the operating member I 2| ismoved to the left switch |23 is reversed, causing motor 81 of unit X tobe reversed, with the result that the throttle valve is immediatelyoperated Vand will continue to operate in one direction, as for instanceto open, so long as the control member I2I is held to the left. When thedesired increase in speed has been obtained the lever I2I may bereturned to the original position whereupon motor B1 is re-establishedat the same speed and in the same direction as, motor I6. leaving thethrottle valve in the position occupied when the lever I2I was returnedto the original position. If it is desired to operate the control in theopposite manner, that is, to close the throttle valve, the controlmember I2| is moved to the right, causing an operation of switch |22 sothat motor 30 of unit X is reversed. It is to be understood that whenswitch |23 is reversed, as above described, the switch I 22 isunchanged, whereas when' switch |22 is reversed switch I 23 isunchanged. Reversal of motor B6 of unit X causes operation of thethrottle valve through the differential mechanism until the desiredposition of the throttle has been obtained, whereupon return or themember I2| to the original position will leave the mechanism operatingat the newly established speed.

The switches |24 and |25 being connected in a manner corresponding toswitches I 22 and I 23 it will be apparent how unit Y can be controlledin the manner described with reference to unit X when unit Y is beingemployed as the master unit through proper setting of the masterselector Z,

The throttling control hereinabove described is of the general typewhich is more fully described and which is claimed in my copendingapplication illed on even date herewith, entitled Control system, SerialNo. 459,412.

In carrying out the present invention it may be desired to employgenerators involving D. C. exciters which require commutators. Sincecommutators may cause undesirable sparking in aircraft operated at highaltitudes electrical devices equipped with commutators are preferablyencased so that they operate at substantially constant pressure.

In practice it will usually be desired to connect the output 'of theseveral power generators G. I have provided the overrunning clutches Jbetween each motor C and its generator G, so that as One generator isstarted before the other, or is running ahead of the other, it can feedinto the other and cause it to operate as a motor until it is up tospeed, at which time it will be in phase and function as a generator.

In the form of the invention illustrated in Fig. 3 I employ a pressuregenerator or pump A' of a positive displacement type which will deliverfluid under pressure at a rate depending upon the speed of operation ofthe engine B. With this type of pump or pressure generator it isimpractical to attempt to regulate the delivery of fluid by controllingthe amount of fluid supplied to the pump and, therefore. the regulationof the 76 fluid is accomplished by control of the dischargediluid. 5,

In the form of the invention illustratedin Fig. 34 the oil delivered bythe pump A' after passing the cut-olf means 20 and check valve2|,qenters a pressure regulator or pressure relief device 'III whichoperates to allow fluid to pass to the oil supply line I2 at apredetermined pressure, any excess being discharged through the outlet'Il which connects with the supply line II so that it is returned eitherto the pump A' or to the reservoir I3. The pressureQ regulating device1li may be of any suitable type, there being various .devices of thischaracter suitable for the purpose and well-known to those skilled inthe art. The present invention is in no way concerned with the detailsof such elements of the system and, therefore, the details have beenomitted from the drawings.

With the pressure regulator 'I0 receiving oil from the pump A' andcontrolling the pressure supplied to the supply line I2, it isunnecessary to provide an accumulator such as is illustrated in the formof the invention shown in Fig. 1. If desired. however, an accumulatorcould be incorporated in the system. If the accumulator is eliminated asshown in the drawings it may still be desirable to provide thermalcontrol of the fluid passing through the supply line I2 to the motor Cin which case a suitable thermal `medium such as a heating or a coolingmedium, as the circumstances require, may be circulated through amanifold 80 provided in connection with the supply line I2, thecirculation of the thermal medium being controlled by a valve IIregulated by a suitable thermostat 32.

Except for the difference in the manner of supplying fluid underpressure to the line I2 the system shown in Fig. 3 may correspond withthat shown in Fig. 1. In Fig. 3 the elements of the system correspondingto those shown in'Flg. 1 are numberedV correspondingly. The operation ofthe system illustrated in Fig. 3 is substantially the same as thatillustrated in Fig. 1, except for the manner in which the fluid pressureis generated and regulated. .In the system shown in Fig. 3 the pump'A'will deliver fluid under pressure at a rate depending upon the speed atwhich the engine' B is operated. Suillcient fluid is passed by thepressure regulating valve lII to maintain the desired pressure in thesupply line I2. The excess is bled off or discharged into the supplyline II for recirculation.

In practice a wobble plate type of pressure generator Az may be used asshown in Fig. 6 o! the drawings. The usual wobble plate type ,of pump orpressure generator is positive in action and the volume oi' fluiddelivered is governed by the wobble plate the wobble plate and in suchrunning to regulate the supply to the generator as in Fig. 1 or to bleedoil" excess fluid under pressure as in the case shown in Fig. 3.

Having described only typical prefer: ed foi-mr.: and applications oi myinvention. I do not wish to be limited or restrictedy to the specificdetails herein set forth, but wish to reserve to myself' any variationsor modications that may appear to those skilled in the art or fallwithin the scope of the following claims.

Having described my invention, I claim:

1.'In an electrical generating system of the character described, asource of power, an alternating current generator, a fluid motorconnected with the generator for operating it, a iluid pressuregenerator connected with the source of power to be driven thereby, ailuid connection delivering iluid under pressure from the pressure suregenerator connected with the sourd: of I5 power to be driven thereby, ailuid connection delivering iluid under pressure from the pressuregenerator to the motor, means whereby the iluid under pressure isthermally regulated to enter the motor at a predetermined temperature,zo

and a control for the iluid whereby it is delivered to the motor at apredetermined rate and pressure.

- 3. In an electrical generating system of the character described, asourceff power, an alternating current generator, a iluid motorconnected with the generator for operating it, a fluid pressuregenerator connected with the source of power to be driven thereby, ailuid connection delivering fluid under pressure from the pressuregenerator to the motor, a iluid supply means receiving fluid from themotor and supplying it to the pressure generator, and a control for theuid whereby it is delivered to the motor at a predetermined rate andpressure, and means thermally controlling the fluid at the supply meansand at said uid connection whereby the temperature of the fluid ismaintained substantially constant.

4. In an electrical generating system of the character described, asource of power, an alternating current generator, a fluid motorconnected with the generator for operating it, a fluid pressuregenerator connected with the' source of power to be driven thereby, afluid connection delivering fluid under pressure from the pressuregenerator to the motor, and a control for the fluid whereby it isdelivered to the motor at a predetermined rate and pressure, the controlincluding means regulating the pressure of the vfluid delivered by thepressure generator, an orifice iltting regulating the rlow to the motor,and means maintaining a predetermined back pressure on the motor.

5. In an electrical generating system of the' 65 character described, asource of power, an alternating current generator, a fluid motorconnected with the generator for operating it. a fluid pressuregenerator connected with the source of power to be driven thereby, afluid connection no delivering iluid under pressure from the pressuregenerator to the motor, a iluid Supply means receiving iluid from themotor and supplying it to the pressure generator, and a control for thefluid whereby it is delivered to the motor at a predetermined rate andpressure, the control including means regulating the pressure of thefluid delivered by the pressure generator, a ilow regulator in saidconnection immediately ahead of the motor, and a ilow regulator betweenthe motor and the iluid supply means.

6. An electrical generating system for use with a source of power havingtwo engines including i two generating units, one connected with eachtor, a fluid motor for driving the generator, a fluid pump driven by theengine, and a iluid pressure connection carrying fluid from the pump tothe motor and a return ,connection carrying iluid from the motor to thepump, and means interconnecting the units including a iluid connectionbetween the pressure connections and a fluid connection between thereturn connections.

7. An electrical generating system for use with a source o! power havingtwo engines including two generating units, one connected with eachengine and each including, an electrical generator, a fluid motor fordriving the generator, a tluid pump driven by the engine, and a llluidpressure connection carrying fluid from the pump to the motor and areturn connection carrying fluid from the motor to the pump, and meansinterconnecting the units including a iluid connection between thepressure connections and a iluid connection between the returnconnections, and means at each pump operable to close the pressureconnection and the return connection at said. pump upon failure of saidpump to generate pressure.

8. An electrical generating system for operation by a source of powerhaving two engines including two generating units, one connected witheach engine and each including, an electrical generator, a luid motorfor driving the generator, a fluid pump driven by the engine, and ailuid pressure connection carrying iluid from the pump to the motor anda return connection carrying fluid from the motor to the pump, and meansinterconnecting the units including a fluid connection between thepressure connections and a iluid connection between the returnconnections, and means in the pressure connection to each motor operableto close said connection upon failure of the motor.

9. An electrical generating system for operation by a source of powerhaving two engines including two generating units, one connected witheach engine and each including, an electrical generator, a uid motor fordriving the generator, a fluid pump driven by the engine, and a y iluidpressure connection carrying fluid from the pump to the motor and areturn connection carrying iluid from the motor to the pump, and meansinterconnecting the units including a fluid connection between thepreure connections and a fluid connection between the returnconnections, and a means in connection-with each motor and the iluidconnection that is between the return connections whereby upon failureof the motor the ilid connection is closed to flow from the return ofthe other motor.

10. In an electrical generating system, two units each including analternating current pcwer generator, a power means for driving the powergenerator, an overrunning clutch drive between the power means and powergenerator, and a throttle for controlling operation of the powergenerator, the output of the power generators of the units beingconnected, and a control system for ,the units whereby one of them isregulated to operate in synchronism with the other including analternating curre t control generator connected to operate with thepower generator of the regulated unit, an alternating current controlgenerator connected to operate with the power generator of the saidother unit, a ditferential mechanism for operating the throttle of theregulated unit, and oppositely running synchronous motors operativelyconnected with the engine and each including, an electrical genera- 'udifferential mechanism so the throttle is opermeerl when the motors areout one motor being energized from one Vcontrol gen-` system. for the oisynchronism,

crator andthe other motor being energized from the other controlgenerator.

l1. In an electrical generating system, two units each including analternating current power generator, a power means for driving the powergenerator. and a` throttle for controlling operation of thepower'generator, and a control units including, two oppositely operatingsynchronous motors at each unit, a differential mechanism for each unitoperatively connected with the throttlethereof and driven by the motorsthereof so the throttle is operated when the motors are out ofsynchronism, an alternating1 current control generator operating withthe power generator ofeach unit, and means whereby the motors of oneunit are both energized by the control generator of that unit while themotors of the other unit are energized one by the control generator ofone unit and the other by the control generator of the other unit.

12. In an electrical generating system, two

units each including an alternating current power generator, a powermeans for driving the power generator, and a throttle for controllingoperation of the power generator, and a control system for the unitsincluding, two oppositely operating synchronous motors at each unit, adifferential mechanism for each unit operatively connected withthethrottle thereof and driven by the motors thereof so the throttle isoperated when themotors are out of synchronism, an alternating currentcontrol. generator operating with the power generator of eachunit, andmeans whereby the motors of one unit are both energized by the controlgenerator of that unit while the motors of the other unit are energizedone by the control generator of one unit and the other by the controlgenerator of the other unit, the said means including a selecting switchwhereby either of the units may be established as the one having itsymotors energized by the same control generator.

l3. In an electrical generating system, two units each including analternating current power generator, a power means for driving the powergenerator. and afthrottleior` controlling operation of the powergenerator, and a control system'for lthe units including, two oppositelyoperating synchronous motors at each unit, a differential mechanism foreach unit operatively connected with 4the throttle thereof and driven bythe motors thereof so the throttle is operated when the motors are outofsynchronism, an alternating current control generator operating withthe power generator of each unit, means whereby the motors of one unitare both energized by the control generator of that unit while themotors of the other unit are energized one by the control generator ofone unit and the other by the control generator of the other unit, andregulating means for varying the operation of either of the motors ofthe unit in which the motors are energized by the same generator wherebythe throttle ot that unit can be operated to change the speed ofoperation of the power generator of that unit.

14. In an electrical generating system, two

units each including an alternating current powergenerator, a powermeans for driving the powerl generator, ,and a throttle for controllingoperation of the power generator, and a control system for-the unitsincluding, two opposltely operating synchronous motors at each unit, adifferential mechanism for each unit operatively connected with thethrottle thereof and driven by the motors thereof so the throttle lsoperated when thev motors are out of synchronism, an alF ternatingcurrent control generator operating with the power generator of eachunit. and means whereby the motors of one unit are both energized by thecontrol generator oi' that unit while the motors of the other unit areenergized one by the control generator of one unit and the other by thecontrol generator o1' the other unit, the said means including aselecting switch whereby either of the units may be established as theone having its motors energized by the same control generator, andregulating means for varying the operation of either of the motors ofthe unit in which the motors are energized by the same generator wherebythe throttle of that unit can be operated to change the speed ofoperation of the power generator of that unit.

` ARTHUR L. ARMENTROUT.

